Modern vehicles, in particular hybrid electric or electric vehicles, comprise high-voltage on-board power system branches or high-voltage components, e.g., traction batteries, electric machines, power electronics and/or supercapacitors, whose operating voltages are much higher than 60 volts and may be higher than 450 volts. Voltages over 60 volts are extremely dangerous to humans and animals. The high-voltage components are therefore fitted with various contact protection elements, which activate upon signals of possible danger to humans and/or animals. For example, the contact protection elements may include locking elements on the plug contacts or plug connections of the high-voltage components or the housings thereof. The contact protection elements are activated if the plug contacts or plug connections of the high-voltage components are separated or the housings of the high-voltage components are opened.
Furthermore, modern vehicles may include contact protection circuits comprising electrical interlock loops (interlock loop circuits). The contact protection circuits monitor the contact protection elements using the interlock loops. If the contact protection elements are activated in the aforementioned manner, the interlock loops are electrically interrupted. If the corresponding contact protection circuits identify interruptions of this kind in the interlock loops, they send corresponding control signals to the affected high-voltage components and deactivate them. The high-voltage components may be deactivated by electrically isolating the high-voltage components from the high-voltage on-board power system branch or from the on-board power system, and/or by switching off or by discharging the high-voltage components.